Polarizers play an important role in directing or rearranging light and are used in numerous applications from photography to liquid crystal displays (LCDs). Consumer demand for products that use polarizers has created an aggressive and competitive marketplace for manufacturers of large and small LCD devices, aircraft windows, medical imaging equipment, solar energy collectors and other applications not yet realized. In relation to LCDs, the performance of a polarizer determines not only the amount of transmitted light that reaches the viewer, but also the contrast of the viewing platform. The materials and costs related to manufacturing these polarizers result in a high cost to the buyer. In an effort to achieve an edge in the market, manufacturers are continually looking for lower cost polarizer components and construction and fabrication methods without sacrificing quality and performance.
“Absorptive” polarizers, i.e., a linear polarizer where the unwanted polarization states are absorbed by the device are known in the art. A typical “absorptive” polarizer is usually structured in layers comprised of two protective films, two sheets of triacetate cellulose (TAC), one layer of polyvinyl alcohol (PVA), an iodine complex, and several surface treatments and adhesive layers. The most common absorptive polarizer is a “wire grid” polarizer which consists of a plurality of a parallel array of metal wires on a transparent substrate, typically glass or clear polymer film, placed in a plane perpendicular to the incident beam. The grid consists of both a metal medium (the conductor) and a dielectric. How the wire grid polarizer affects light, depends on the size of the grid and the width and pitch of the conductor and dielectric mediums, as well as the thickness of the substrate.
Most polarizers are comprised of many layers which are susceptible to de-lamination caused by moisture and/or heat, as well as the aging process often associated with typical non-wire grid polarizers. The layers are produced utilizing chemical compounds which may have negative effects on the environment. In addition, the current manufacturing processes result in a very low production yield of approximately 70%. Therefore, there is a need for a polarizer with less environmental impact in the manufacturing process and a higher production yield.
In the second quarter of 2009, the largest market share of the global polarizer market is the thin film transistor liquid crystal display (TFT-LCD) sector at 95%. Of this, 57% of the TFT-LCD market was for LCD TV-use polarizers. Other uses within this sector are computer monitors, mobile phones, video game systems, navigation systems, projectors and many more.
Most polarizers are woefully inefficient and in an LCD application allow too much light to pass through, requiring the use of other layers to further reduce the amount of transmitted light. Therefore, there is also a need for a more efficient, durable and reliable polarizer that is capable of controlling the passage of light without the vulnerabilities and high costs associated with the use of multiple layers of films and substrates.